Fluid flow filter and method of making and using

ABSTRACT

A filter well suited for paint arrestor usage having a monolithic high loft manmade fiber body with a convoluted flow contact surface. The filter is preferably formed by a convoluter as in one with a roller set and blade cutter to form mirror image fiber filter sheets from a received fiber batt. Provided is a well mixed proper fiber blend, such as one having a set of fibers made of a majority of course fibers joined by way of thermal bonding fibers which facilitate, during convoluting, formation of a crisp cut and high integrity three dimensional surface, as in one of rows of peaks separated by valleys. The projection/recess arrangement over the flow contact surface as well as the thickness and relative projection-to-base dimensions are arranged to provide a high paint holding capacity without too fast a load up of, for example, paint particles and while avoiding too great of a pressure drop within that load up time.

FIELD OF THE INVENTION

The present invention relates generally to filters for fluid streams andmethods of making and using the same. The subject matter of the presentinvention is inclusive of three dimensional surfaced filters ofnon-woven material with a suitable fiber constitution. The fiber battrecipe used in the construction of the filters is well suited forforming the filters in a convoluting process and for use of the filtersas a paint arrestor.

BACKGROUND

Many materials and combinations of materials have been utilized asfiltration media for fluid filters to remove solid or liquid particulatefrom fluid streams. Fluid filters are found in use in commercial spraybooths such as commercial paint spray booths and, when so utilized, areknown in the art as paint arrestors. The commercial paint spray boothsutilize controlled airflow to direct overspray away from the articlebeing painted. This overspray is then exhausted from the booth through afiltration system comprising paint arrestors.

The performance or capabilities of such fluid filters are generallyjudged according to three main criteria:

-   -   A) Particulate Removal Efficiency;    -   B) Holding Capacity; and    -   C) Pressure Drop.

Particulate removal efficiency of a filter is the ability of the filterto capture and retain particulate. For example, with respect to paintarrestors, efficiency is a representation of the percentage of the totalpaint particles entrained in the air stream exiting the booth that arecaptured by the filter.

Holding capacity is the amount of particulate which can be retained bythe filter before the pressure drop becomes so great that the filtermust be cleaned or replaced. Typically the test is stopped at 0.5 in.water and this represents the point at which a filter is typicallyexchanged due to airflow restriction. Proper airflow through the paintspray booth prevents quality issues with the painted surface. Relativeto paint arrestors, paint holding capacity is the weight of the paintparticles, solubolized, suspended, or in aerosol form, that the filterhas captured and held for the time period specified. Paint holdingcapacity thus is determinative of the effective life of a filter. Whendealing with disposable paint arrestors, the effective life has a directbearing on the overall costs to a paint spray booth operator. Also,testing of paint arrestors also frequently records the amount of “runoff” of paint particles from a filter. For example, with a verticallyarranged filter, the run off includes particles that impact the filterbut are not captured by the filter due to, for example, vertical flowoff the filter to an underlying surface as in a liquid drain facility.As the efficiency determination for a filter includes the relativeamount of captured paint particles to those generated, any run off priorto the holding capacity being reached results in a lowered efficiencyrating for a filter, and thus a desirable filter is one with littlerun-off.

Pressure drop for a given flow rate of fluid through the filter isutilized as a measure of the power required to move the fluid streamthrough the media. Thus, for paint arrestors, pressure drop, initial andfinal, is the pressure differential as measured in the air stream acrossthe filter before loading and after loading with paint. Pressure dropcan thus affect the airflow in the booth and the subsequent ability toremove overspray from the paint area.

Spray booths are used in a variety of industrial applications as in theapplication of paint to many different products. A number of differentspray atomizing application techniques can be used in such spray boothsor in other spray environments. One of these techniques is an airatomization technique wherein coating or paint particles are mixed withan air stream being ejected from a spray gun and the air stream isdirected to the product being coated. Another spray applicationtechnique example is an airless atomization technique wherein thecoating material is atomized and propelled by hydraulic pressure to theproduct being coated. Yet another spray application technique example isan electrostatic spraying technique. In a typical electrostatic setting,the product to be coated is grounded and the coating material isatomized (either by an air or airless technique) and is electricallycharged. As a result, the coating materials are deposited on the productdue to the electrical attraction of charged coating particles to theproduct being coated.

Regardless of the spray technique that is used, a paint spray booth iscommonly employed to contain, for example, evaporating solvents and tocapture airborne atomized paint particles to minimize their impact onthe environment and to protect painters from being unnecessarily exposedto the solvents and paint particles used in the coating process,particularly those that may be toxic. In fact, the use of spray boothsis normally required for most liquid paint spray applications by federalor state regulatory agencies, including, in particular, the U.S.Environmental Protection Agency. Moreover, spray booths tend to enhancethe quality of the finish being applied to a product being coated byproviding a clean environment for the application of liquid coatings tothese products.

In such spray booths, it is desirable to maintain a consistent, steadyand uniform flow of air throughout the booth. Among other things, theconsistent air flow prevents the accumulation of partially driedoverspray on an object being coated so that the appearance of the objectis not marred and tends to assist in providing the product with aquality finish. Moreover, spray booths prevent the accumulation ofhazardous concentrations of potentially explosive solvent vapors. Infact, environmental clean air standards require that the emissions fromspray booths must not include more than certain levels of particulates.

To remove paint particulates from the air being exhausted from a spraybooth, a common practice is to employ a replaceable fibrous filter whichwill trap the majority of these paint particulates. These filters soonbecome clogged with such particulates so that the air flow through thespray booth tends to be substantially reduced, thus decreasing the airflow past the worker inside the booth and the products being coated.Moreover, the spray booth has to be shut down to replace such cloggedfilters (once per eight hour shift is not uncommon).

Typical paint arrestors or paint filters utilize flat or two dimensionalsurfaced sheets of non-woven fiber media. These filters can havelaminated scrims, varying densities within the filters, and layers ofvarious non-wovens of different constructions and appearances (e.g., seeU.S. Pat. No. 6,231,646 to Schweizer et al.). In some cases, multiplefilters of various constructions are used in series. High efficiencyfinal filters can be pleated or sewn into bags to increase surface area,in an effort to lower pressure drop while maintaining higherefficiencies. In many paint spray booths, initial filtration isaccomplished using flat sheets of non-wovens of various thicknesses.Expanded papers or laminated non-wovens that are slit and stretchedproducing voids (commonly referred to as paint pockets), can be added tothe flat sheets in an effort to facilitate higher efficiencies and paintholding capacities.

There is utilized in the art disposable fluid filters comprised of abatting of, non-woven, fibrous, fluid material having surface patternson a fluid contact surface. Examples are found in, for example, U.S.Publication No. 2006/0000196, U.S. Pat. No. 4,007,745 to Randall et al.and U.S. Pat. No. 5,658,641 to Berrigen et al. While U.S. PublicationNo. 2006/0000196 fails to describe how its filter is formed, each ofU.S. '745 and U.S. '641 feature a compression technique wherein thefiber media is fed through a pair of comparison rollers to form asurface pattern on one side of the compressed batting (e.g., U.S. '745involves a heated patterned roll; while U.S. '641 features one of thetwo compression rollers traveling at a high speed to form wrinkleindulations in the filter surface).

U.S. Pat. No. 6,071,419 describes first and second fluid permeablelayers of non-woven fiber batting with the upstream layer formed withpaint pockets as by a slit and stretch technique.

U.S. Pat. Nos. 6,740,610 and 6,500,292 describe a non-woven fiber padfor use in futons, mattresses, upholstery and the like having aconvoluted surface formed by cutting a non-woven fiber batt having aplurality of low melt synthetic fibers. The non-woven batt is compressedgenerally toward a cutting device by a pair of counter-rotating drumshaving convoluted surfaces. A heated wire cutter is preferably utilizedto form the desired contour pattern (reference is made to band saw useas an alternative in the '292 patent). The requirements associated witha comfortable futon or the like (e.g., a smooth skin surface due tosurface fusing) are considered far removed from the characteristicsassociated with a filter such as a paint arrestor as explained ingreater detail below.

U.S. Pat. No. 4,772,443 describes a fluid filter formed by manufacturingrandomly disposed structure fibers and a thermoplastic binder fiber. Theinterstices between the fibers are fixed by applying a latex resin tothe batting which is described as fixing the pore sizes of the filteringmedia before the filtering media is molded into the desired shape.

U.S. Pat. No. 6,159,258 discloses air filter elements of foam with anupstream surface area of peaks and valleys.

U.S. Pat. No 4,603,445 to Spann describes convolution assemblies usedfor contouring foam pads for cushioning purposes. As described in Spann,a convolution machine cuts a single piece of foam into two complementarypieces with contoured surfaces generated by the convoluter cut. The cutis done via a horizontal band saw, usually a smooth, practicallycontinuously honed blade with a wedge shaped support. The resilientmaterial is fed into the convoluter, and is compressed in a definedmanner, based on the “tooling”. This tooling is assembled on two drivenrollers that run parallel and on either side of the convoluter-cuttingblade. As the rollers turn, the foam pad is fed into the machine,compressed by the tooling, and cut in the compressed state by theconvoluter blade. As the cut resilient material recovers from thecompression provided by the convoluter tooling, a contoured cut surfaceis formed on each separated foam sheet with the three dimensionalpattern depending on the design of the tooling (e.g., the formation ofsinuous or wave-like ridges). In general, convolution patterns aredesigned such that the two resultant products obtained are of the samemass, although this does not necessarily have to be the case.

While convoluting foam provides relatively consistent product outputeach time when the other factors associated with the foam material aremaintained consistent, the inventors have determined that there isdifficulties associated with convoluting non-woven material in an effortto provide filter media. That is, while a convoluted non-woven fiberlayer may be well suited for inclusion within a mattress or the like, itmay not be deemed commercially viable for filtering (e.g. a paintarrestor) as there are additional criteria involved with making acommercially viable non-woven fiber filter for use in a setting such asa paint spray booth. In other words, a non-woven fiber material such asone used for a mattress, can have varying density levels throughout itsthickness and across its surface due to the fiber recipe characteristicsand/or the formation process without being considered non-workable.Further, a high loft fiber composition best suited for cushioning andbedding material is able to have different characteristics than thatused in the formation of a suitable filter for paint arresting as thereis not the level of concern for consistency and surface integrity. Alsoconvoluting non-woven (particularly high loft non-woven material) alsopresents the additional problem of inconsistent surface cutting resultsand/or a change in the media characteristics at the cut surface (e.g., afraying of fiber ends or tearing of surface sections). Also, for manyfilter uses, it is preferable to have a convoluter that utilizes anon-heated material cutting device as, while a heated cutter can avoidsome of the issues of tearing and fraying, for many fiber battcompositions it would alter the initial fluid impact surface of thefilter and lessen the penetration potential of the filter and hence itsholding capacity, etc.

While non-woven batting is relatively inexpensive and thus good fordisposable use, it is prone to poor surface projection integrity (e.g.,peak integrity). Attempts by the inventors to convolute fiber blends hasresulted in peaks which were torn more than cut in the convolutingprocess. The peaks were also very fragile with loose fibers hanging orlaying on top of the peaks. Also, subsequent handling of the convolutedhigh loft non-woven product resulted in further degradation of theprojections or peaks. Loose fibers are deemed problematic when thefilter is intended for use as a paint filter. This is because loosefibers introduce the potential for fibers to find their way into thebooth and on the object being painted.

In addition, while convoluting foam material in a production setting isrelatively straightforward due to the material involved (e.g.,polyurethane foam), the processing of convoluted fiber in a productionsetting directed at filter usage is much more difficult in view of thedifferent characteristics of the material involved, the interplay ofthat material with a convoluter equipment, and the end productioncharacteristics required. For example, the inventors efforts involved inconvoluting high loft, non-woven filter material has shown thathigh-loft recipes and surface patterns play a role in the resultantfilter characteristics.

For example, an improper fiber recipe (fiber blend or mixture and/orfiber bonding means utilized) and/or an improper cutting techniqueand/or an improper surface pattern can lead to problems such asill-defined pattern generation both within a single convoluted piece aswell as between convolution runs for what is considered the samestarting material. Additionally, inventor testing has determined that,in addition to fiber blend recipes playing a role in whether aconvoluted end product is suitable for an end use in, for example, apaint spray booth application, the surface pattern itself can play arole both in removal efficiency and in product acceptability. That is,the nature of high loft, non-woven material is such that during, forexample, a peak/valley convolution processing, there resulted in manyinconsistencies relative to peak height, base thickness, peakdefinition, peak and base height ratios, etc.

SUMMARY OF THE INVENTION

The subject matter of the present invention is inclusive of a non-wovenmedia that provides good filtering characteristics (e.g., higher airflow, less pressure drop, good holding capacity and a longer period oftime of use), particularly in the field of particle (e.g., liquid paintparticle) filtering. The subject matter of the present invention is alsodirected at convolution techniques for convoluting non-woven filtermedia (e.g., high-loft) with good usage and handling characteristics.The inventors have determined that with proper fiber blend and densityselections the “crispness” or clarity of the contoured cut as well asthe durability of the final product can be improved. A rotating bladeloop cut is preferred although, in certain settings, other surfacecontouring means are featured under the subject matter of the presentinvention inclusive of other blade based forms of separationfacilitation means (e.g., a reciprocating non-loop blade or sheetblade), as well as alternate separation facilitation means as in aheated cut wire technique, as well as alternate overall filter formationtechniques as in filter molding techniques, etc.

This fiber blend, density selection and/or fiber bonding means canpromote high performance under the present invention relative toparticulate removal efficiency, holding capacity, and pressure drop. Inother words, the present inventive subject matter is inclusive of afilter that can be effectively produced via a convoluting method whileproviding a filter product with a proper pattern, blend, surfaceintegrity, weight and thickness as to provide a highly efficient filterthat is commercially viable for many filter uses including those filterusages having a high particulate throughput and/or high sensitivity tocontaminant potential.

The inventors have further determined that fiber blend is highlyinfluential with respect to paint filtration capability. Finer deniers(e.g., those at or less than 6 denier) in a blend capture smallerparticles and usually exhibit higher filtration efficiencies. The term“denier” is a unit of weight for measuring the fineness of threads orstrands of, for example, silk, rayon, nylon, etc. While not intended tobe limiting relative to the present application, the term denier isoften defined in the traditional sense as: weight in grams/9000 m for asingle strand or filament. Thus, for a 15 denier fiber a single 9000 mlength strand would weigh 15 g. The downside is that the finer denierscreate a filter with a higher pressure drop reducing air-flow. Filtersutilizing finer deniers typically “load-up” with paint faster reducingthe life span of the filter. For a commercial operator of paint booths,extending the length of time between filter changes saves money infilter costs and increases the time efficiency of booth utilization.Thus, moving to a higher denier blend allows the filter to capture morepaint before restricting airflow. However, the converse of the firstexample is true for the coarser denier filters. The courser denierfilters are more apt to exhibit lower filtration efficiencies (allowingmore particles to flow through the filter). More particles downstream ofthese filters will decrease the life span of traditional higherefficiency filters if utilized downstream in the system. If downstreamfilters are not used, then excess particles passing through the filtercould collect inside ductwork or even passthrough to ambient air causingobvious problems.

When using coarser deniers, it has been found that increasing the weightor mass and the thickness of the filter generated acceptable filtrationefficiency while keeping the advantage of higher paint holdingcapacities. The current blend embodiments of the present invention allowfor good efficiencies and excellent paint holding capacities.

The fiber blend or recipe is also influential in facilitating consistentand repeatable convoluting of the fiber substrate. The current blendembodiments of the present invention also have been developed (alongwith the above considerations) to facilitate a finished product withdefined convoluted peaks. In other words, it has been determined that aproper blend allows definitive peak shape formation and also allow goodpeak and surface integrity.

There is further avoided with the inventive blends of the presentinvention loose fiber release into the paint area or downstream. Anyloose or separable fiber material that can find its way back toward theproduct subject to a paint or application process can lead to problems.For example, loose fibers can be particularly problematic in a paintbooth application due to the chance of the fibers becoming entrapped ona freshly painted surface. Also, a preferred technique of cutting thefibers is a mechanically driven blade as opposed to a heated resistancewire as contact cut heating, while lessening the potential for loosefibers, can alter the filtering characteristics in the cut surfaceregion and thus is a less preferable cutting technique under the presentinvention.

The subject matter of the present invention includes a fiber basedfilter (e.g., a high loft, non-woven fiber based filter is preferred)which, by way of an appropriate configuration and structure composition(e.g., fiber recipe) provides a fiber filter batt that can be convolutedwhile avoiding problems associated with the prior art (e.g., lack ofconsistency in the structure of the resultant filter such as poorstructural surface presentation from filter to filter produced and theavoidance of torn or poorly defined surface contouring which could, ifpresent, lead to the above described problem of filter materialgenerated contamination).

The convolution process can produce two (or more as with a multi-bladearrangement) fiber filter sheets per single fiber batt fed into theconvoluter. Under the present invention, there is achieved consistencyof the finished convoluted fiber filter sheets, both with respect to themirror image pair of convolutions from a single source fiber batt (e.g.,good mirror image consistency of the two sides, top and bottom derivedfrom a fiber batt) and from common type fiber batt to common type fiberbatt produced by the fiber batt production assembly (e.g., consistentand even density levels through the thickness and along the length ofeach filter sheet produced from a common type fiber batt). Thisconsistency is derived to some extent on the recipe utilized with itsfiber types, deniers and binding characteristics (relative to battsdesigned to have the same general composition and structure asvariations from batt to batt are also possible with adjustments in thenon-woven batt forming means or batt forming assembly of the presentinvention). The fiber filter sheets produced in the convolution processcan form a resultant filter directly off the convoluter or the sheetscan be further processed as in cutting with a cutter to form smallersections from the sheets meeting the desired resultant filter size (e.g.a vertical cutting blade moving relative to a horizontally conveyedfiber filter sheet).

In order to improve the performance of the blend for paint arrestance,the majority of the fibers in the blend is preferably in the coarsedenier fiber category. For the purpose of this present discussion,coarse denier fibers are about 15 denier and higher. Also, preferablythe majority of the fibers are in the 40 denier range. The coarserdenier fibers are considered under the present invention to enablebetter paint/air separation and paint holding capacity. Also, thecoarser fibers are considered under the present invention to enable thefilter to maintain a higher air-flow, less pressure drop, for a longerperiod of time during use.

A preferred embodiment of the present invention also features relativelyhigh depth in the filter surface contouring as in relatively high heightin convolution formed peaks relative to the base (with “high” being forexample greater than 50% of the total height of the resultant filter). Apreferred “high” height embodiment is also preferably one with a heightof 75% or more of the total height of the resultant filter with a rangeof about 50 to 85% being well suited for many applications of thepresent invention. After 75% the thinness of the base can present someproblems relative to, for example, integrity and handling. Thus, a rangeof 50 to 75% peak height depth represents a preferred more universalapproach. It is considered that with the higher depth of the valleysbetween projections, preferably also with relatively larger (e.g., equalto or greater than 2.0 inch) peak spacing, the filter exhibits a higherpaint holding capacity even beyond that provided with the shallowerdepth arrangement produced under the techniques of the presentinvention. For example, in a first embodiment of the invention there isa pattern having small height peaks (with “small” being, for example,equal to or less than 50% of the total height of the filter and a lesserdistance between the peaks (e.g., less than 1.125 inches) relative tothe above noted more preferred embodiment having high peaks and deepervalleys and relatively large peak spacing from row to row (e.g., 2.0±50or more inch peak spacing). While even the “shallower” arrangement isconsidered to represent an improvement over the prior art, it isconsidered that by using a larger pattern, wider base and more distancebetween peaks, there is achievable a further improvement in consistentfilter processing.

Experimental findings indicate a preferred embodiment is one that has amaximum feasible depth of cut that is achievable under the techniquesutilized by the present invention (e.g., a convoluter such as thatdescribed herein) at the minimal peak spacing, which provides maximumfiltration surface area. In addition to the increased filtration surfacearea achieved, a preferred embodiment also allows a more robust andrigid peak compared to designs that incorporate shorter peak to peakspacing under the techniques utilized by the present invention.

Furthermore, it is considered by the inventors that by using the coarserdenier fibers along with a higher percentage of binder fiber (e.g., apercentage of core and/or solid binder fibers representing at least 15%of the overall weight of the fiber mix used in the production of thefiber batt), the convolute pattern becomes even more greatly definedwith no apparent peak deformation and/or loose fibers at the peaks. Asnoted above, loose fibers at the peaks would be problematic in a paintbooth application due to the chance of the fibers becoming entrapped ona freshly painted surface.

In addition, processing of convoluted fiber consistently in a productionsetting is difficult. Of particular difficulty is avoiding in aconvolution process a poorly defined pattern or loose fibers at thepeaks which, if present would render the filters not commerciallyacceptable for uses preferred under the present invention. As well, theability to control the consistency of the final product with respect topeak height, base thickness, peak definition, etc. is difficult in manyproduction settings. Inconsistent peak and base height ratios willaffect the test results and subsequent performance in a real worldapplication. This can further lead to a high (e.g., 50%) final productscrap rate. Under preferred embodiments of the present invention,however, through a proper pattern, proper processing technique, andproper blend, weight, and thickness of the filter (and associated fibersheet under a preferred convolution process) there is considered by theinventors to be provided a highly advantageous filter that is furtherconsidered commercially viable.

There is featured under the subject matter of the present invention amethod of producing a filter comprising providing a non-woven fiber battand convoluting the non-woven fiber batt to produce a fiber filter sheethaving a convoluted flow contact surface. Also, preferably the step ofconvoluting includes feeding the fiber batt between a pair of rotatingtooling members and splitting the fiber batt into at least two fiberfilter sheets with respective convoluted flow contact surfaces. Further,the tooling members preferably include projections which result in peakand valley surface contouring in the fiber filter sheets with the peaksrepresenting 50% or more of total thickness of the fiber filter sheet.Also, in a preferred embodiment the peak and valley surface contouringincludes sinusoidal or zig-zag shaped elongated ridges as peaks in thepeak and valley surface contouring, and wherein the total fiber sheetthickness is 1 to 4 inches and rows of peaks that are spaced apart for2.0±0.75 inches.

Under a preferred method a fiber filter sheet is produced from anon-woven fiber batt that has a base (or basis) weight of between 600g/sqm to 2100 g/sqm with a thickness of 75 to 165 mm. Also, thenon-woven fiber batt preferably has a base weight of between 1200 g/sqmto 1800 g/sqm with a thickness of 100 to 150 mm, and is comprised of afirst set of fibers of 15 denier or greater such as non-binder typefibers that are mixed with a thermal binder fiber type. A preferredmethod further includes convoluting a high loft fiber blend comprised ofa first set of fibers representing a majority of fibers in the non-wovenfiber batt and which first set has an average denier of 40 denier orgreater.

An embodiment of the present invention further includes convoluting ahigh loft fiber batt that is comprised of a first set of fibers having adenier value of 15 to 40 denier, a second set of fibers having a deniervalue of 40 to 100 denier and a thermal binder fiber. For example, thefirst set of fibers can represent about 20 to 50% by weight of anoverall fiber blend forming the non-woven fiber batt, the second set offibers can represent about 30 to 75%, and the thermal binder fiber canrepresent about 20 to 40%. In a preferred embodiment the first set offibers represent about 10 to 25% by weight of an overall fiber blendforming the non-woven fiber batt, the second set of fibers representabout 40 to 60%, and the thermal binder fiber represents about 25 to35%, and wherein each of the first and second sets of fibers and thebinder fibers represent different binder fibers. Also the fiber battbeing convoluted is preferably comprised of a high loft non-woven fiberbatt with a density level of 7.5 Kg/m³ to 15.0 Kg/m³.

As an additional example of an embodiment of the present invention, thenon-woven fiber batt is convoluted to form a high loft fiber filtercomprised of a majority of coarse fibers and the fiber filter furthercomprises thermal binding fibers and wherein the majority of coarsefibers of the non-binder type fibers have an average denier of about 40or more. The fiber batt is preferably split into two fiber filter sheetswith the fiber batt thickness being from 1 to 9 inches. Also, as shown,an interface region between each projection and supporting base isformed of a continuous blend of the fibers of said fiber blend.

Further, a preferred method under the present invention includes aconvoluter that produces a plurality of fiber filter sheets with eachfilter fiber sheet being monolithic and having projections and valleysand a base layer below the projections wherein the projections extendfor 50% or more of the total fiber filter sheet thickness, and whereinthe projections define a plurality of rows of sinusoidal or zig-zagshaped projections which are spaced by 2±0.75 inches from row to row andhave peak to peak amplitude spacing along a row of about 2 inches ormore and wherein the slope angle is from 40 to 65 degrees. For example,an embodiment of the invention includes a convoluter that produces aplurality of fiber filter sheets with each filter fiber sheet beingmonolithic and having projections and valleys and a base layer below theprojections wherein the projections extend for 50% or more of the totalfiber filter sheet thickness, and wherein the projections define aplurality of rows of peaks having a side slope of 45 to 60°

An additional embodiment of the invention features a filter comprising afiber filter body having a base and a plurality of projections extendingfrom the base, and wherein the fiber filter body is a monolithic highloft fiber material body that is comprised of a fiber blend having amajority of fibers of or averaging 15 denier or higher and a thermalbinder representing 15% or higher by weight of the fiber blend. Forexample, an embodiment features a fiber filter body that comprises afiber blend having a first set of fibers with a denier value of 15 to 40denier, a second set of fibers having a denier value of 40 to 100 denierand a thermal binder fiber, and wherein the first set of fibersrepresent about 20 to 50% of an overall fiber blend forming the fiberfilter body, the second set of fibers represent about 30 to 75%, and thethermal binder fiber represents about 20 to 40%. Also, the fiber filterbody preferably has a base weight of between 600 g/sqm to 900 g/sqm witha thickness of 50 to 75 mm and the projections extend for 50% or more ofa total thickness of the fiber body and are in the form of sinusoidal orzig-zag shaped rows having a slope angle of 40 to 60 degrees, as in onewith projection rows that are spaced apart by 2±0.75 inches and saidprojections represent about 60 to 85% of the height of said fiber filtersheet and said projections are rounded peak rows with a side wall slopeof 45 to 60°.

A filter such as that described when functioning as a paint arrestorfilter can provide a paint holding capacity of 6.8 pounds or more per 20inch by 20 inch area of the paint arrestor filter before reaching about0.50 pressure drop across the filter.

An embodiment of the present invention further comprises a filter formedof a monolithic, high loft fiber filter body having a majority ofnon-binder fibers of 15 denier or more and being bound by a thermalbinder representing 15% or more of the total fiber weight of the highloft fiber body, and the high loft fiber body having a basis weight of600 to 900 g/sqm (as produced for example from the splitting of a fiberbatt having 1200 to 1800 g/sqm) and a thickness of 1 to 4 inches, andthe fiber body comprising a base layer and a plurality of projectionsextending off the base layer and the projections being arranged todefine valleys therebetween. The filter is also preferably formed with amajority of the non-binder fibers that are of 40 denier or higher as ina filter with non-binder fibers bonded in a fiber blend by thermalbinder fibers, which thermal binder fibers representing about 20 to 40%by weight of the fiber blend and with the fiber filter sheet havingprojections comprised of continuous rows of peaks and with thoseprojections preferably representing about 60 to 85% of the height of thefiber filter sheet and the projections are rounded peak rows with a sidewall slope of 45 to 60°.

There is further featured under the subject matter of the presentinvention paint arrestor booth comprising an enclosure, one or more ofthe filters such as those described above and a support for the one ormore filters positioned within the enclosure. There is further providedan air flow generator arranged for passing air through the supportedfilters either by a behind the operator forcing forward of air and/or adrawing of air via a downstream fan or the like. Additionally featuredis a method of removing particles as in paint particles by passing astream of fluid containing particles to be removed through an embodimentof the filter of the present invention and assembly a spray booth whichincludes an encompassing housing structure with a support structurecontained in the housing and one or more embodiment of the filter of thepresent invention contained on the support coupled with fluid flow meansfor directing fluid through the housing and past the filter(s).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view, partially cutaway, of a paintspray booth capable of utilizing a paint spray filter incorporatingsubject matter of the invention;

FIG. 1A is a schematic front view, partially cutaway, of anon-convoluted paint spray filter “Sample 1” supported by a conventionalpaint arrester filter support structure;

FIG. 1B is a schematic side view, partially cutaway, of the paint sprayfilter shown in FIG. 1A; and

FIG. 1C is a “Clean Filter” pressure drop versus air velocity graph forSample 1.

FIG. 1D is a pressure drop versus weight of fed paint or “Pressure Drop”graph for Sample 1.

FIG. 1E is a final filter weight gain versus weight of paint fed or“Penetration” graph for Sample 1.

FIG. 1F is a percentage of filter removal versus the weight of paint fedor “% Removal Efficiency” graph for Sample 1.

FIG. 2 is a side elevation view of a contouring assembly for imparting athree dimensional surface pattern in a fiber batt fed in the containingassembly

FIG. 3 is a cut-away front elevational view of the convoluter assemblyin FIG. 2 showing a fiber batt being convoluted into two fiber filtersheets.

FIG. 4 shows a top plan view of a generic representation of a zig-zag orsinusoidal convoluted surfaced filter sheet produced by the convoluterof FIG. 2.

FIG. 5 shows a cross-sectional view taken along cross-section line II-IIin FIG. 4.

FIG. 6 shows a perspective view of a preferred embodiment of theinvention generically shown in FIG. 4.

FIG. 6A shows a perspective view of the dashed-line section shown inFIG. 6.

FIG. 7A is a “Clean Filter” pressure drop versus air velocity graph forSample 2.

FIG. 7B is a pressure drop versus wet paint “Pressure Drop” graph forSample 2.

FIG. 7C is a final filter weight gain versus weight of paint fed or“Penetration” graph for Sample 2.

FIG. 7D is a percentage of filter removal versus the weight of paint fedor “% Removal Efficiency” graph for Sample 2.

FIG. 8A is a “Clean Filter” pressure drop versus air velocity graph forSample 3.

FIG. 8B is a pressure drop versus weight of fed paint or “Pressure Drop”graph for Sample 3.

FIG. 8C is a final filter weight gain versus weight of paint fed or“Penetration” graph for Sample 3.

FIG. 8D is a percentage of filter removal versus the weight of paint fedor “% Removal Efficiency” graph for Sample 3.

FIG. 9A is a “Clean Filter” pressure drop versus air velocity graph forSample 4.

FIG. 9B is a pressure drop versus weight of fed paint or “Pressure Drop”graph for Sample 4.

FIG. 9C is a final filter weight gain versus weight of paint fed or“Penetration” graph for Sample 4.

FIG. 9D is a percentage of filter removal versus the weight of paint fedor “% Removal Efficiency” graph for Sample 4 (with weight of paint “fed”being based on how much is poured into the sprayer and ejected from thesprayer).

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

As explained above, this invention contemplates providing an improvedfluid flow filter for use in, for example, a paint spray booth. Anexemplary embodiment of a conventional paint spray booth with filtersupport structure is shown in FIGS. 1, 1A and 1B, and is identified byreference numeral 10. Paint spray booth 10 includes a pair of sidepanels 12, 14 and end panel 16, and means defining an access 18 to booth10 from the front thereof. Intermediate end panel 16 and access 18 areframe members 20. Frame members 20 like that featured in FIG. 1typically define one or more rectangular frameworks 30 having dimensionsof approximately 36 inches high and varying widths, for example, 24inches wide. Thus, depending on the size of booth 10, one or moreframeworks comprising frame members 20 will be utilized. For example, ifbooth 10 is only about three feet high by two-feet wide, only oneframework 30 will be needed; on the other hand, if booth 10 is to be sixfeet high by four feet wide, two frameworks (two columns three feet highby four feet wide) will be needed, etc. Frame members 30 can take anydesirable shape.

The frame members 30 used in the construction of booth 10 are used tosupport a paint spray filter, such as an filter 28 shown in FIG. 1.Still referring to FIG. 1, paint spray booth 10 is shown to be dividedby filter 28 into a spraying area 72 and an exhaust area 74. An articleto be sprayed (not shown) is typically placed in spraying area 72 whereit is spray painted by an operator in accordance with usual spraypainting operations. Fumes and particulate matter associated with thespraying process are ordinarily exhausted by ventilation means 25communicating with the top 19 of booth 10 to pull the polluted air awayfrom the operator of the paint spray apparatus in a well known manner.

Reference is now made to FIGS. 1A and 1B which illustrate the paintspray filter 28 and framework 30 combination shown in FIG. 1. Paintspray filter 28 is supported on paint arrestor support structure wiregrid 40. The filter support means 40 is shown as having a plurality ofhorizontal numbers 41 through 47 and a plurality of vertical members 31through 35. Horizontal members 41 and 47 define the horizontal edges ofgrid 40 and vertical members 31 and 35 define the vertical edges of grid40. Thus, horizontal members 41 to 47 and vertical members 31 to 35define the perimeter of the grid which extends substantially 36 inchesin the vertical direction and 24 inches in the horizontal direction inthe illustrated embodiment.

Grid 40 further includes a plurality of attachment spikes 50. In thispreferred embodiment six attachments spikes 50 are utilized. The sixattachment spikes 50 are located, respectively, at the intersections ofhorizontal members and vertical members.

Spikes 50 serve as attachment means for holding filter sheet 28 ontogrid 40. As shown in FIG. 3, filter 28 is shown as being a sheet offilter material 60 having planar front and back surfaces 62,64 (a fiberor a foam sheet being illustrative of the prior art filters). Filter 28is shown generally coextensive with the portion of grid 40 defined byhorizontal members 41 and 47 and vertical members 31 and 35. The sheetof filter material 60 is attached to grid 40 by pushing rear face 64onto spikes 50 until rear face 64 is substantially flush against grid40, particularly horizontal members 41 through 47 and vertical members31 through 35. In this manner, rear face 64 of the sheet of filtermaterial 60 substantially covers grid 40 while front face 62 of thesheet of filter material 60 is fully exposed.

The above described spray booth and filter support frame structure arebut one of many types of ventilating enclosure means and filter supportmeans for which the filter of the present invention can by utilized asthere are a wide variety of ventilating enclosure and filter supportmeans suitable for use with a filter falling within the subject matterof the present invention (and thus FIGS. 1, 1A and 1B are provided forillustration background purposes only).

As will become more apparent below, providing a proper pattern, properblend, weight and thickness to a fiber sheet, and preferably also aproper convoluting processing of the pre-convolute fiber batt providesfor a highly efficient filter product which is commercially viable for awide variety of industrial usages including those with large throughput(e.g., a paint arrestor filter which is illustrative of a filter with afrequent replacement requirement (e.g., an each day filter replacementenvironment)). The present invention thus provides for a relativelyinexpensive filter material that still can provide good results in thethree categories of i) particulate removal efficiency, ii) holdingcapacity and iii) pressure drop levels while also avoiding problems offiber contamination and problems associated with production consistencyand quality goals.

Fiber Batt Blend, Weight and Thickness

Providing a proper pattern, proper blend, weight and thickness to afilter of the present invention is facilitated with the formation of anon-woven fiber batt having characteristics that provide for such afilter formation. The filter of the present inventions is preferablygenerated from a high-loft, non-woven fiber batt. In its preferred usagein the present application, the term “highloft” is in reference to (i)lofty, relatively low density nonwoven fiber structures, preferablyhaving a greater volume of air than fiber; (ii) nonwoven materials thatare produced with the purpose of building loft or thickness withoutincreasing weight; and/or (iii) nonwoven fiber products that are notdensified or purposely compressed over a significant portion of theproduct in the manufacturing process of the fiber batt or filterformation starting material.

The highloft nonwoven material of the fiber batt of the presentinvention preferably has a basis weight of 600 to 2100 g/m², morepreferably 1200 to 1800 g/m². The highloft nonwoven material of thepresent invention also preferably has a pre-convolution thicknessfalling between within a range of 40 mm to 225 mm with a thickness rangeof 100 to 150 mm being deemed well suited for many uses of the presentinvention. With this range of thickness for the fiber batt, when using aconvolution process to generate a desired three dimensional surface(s)in the resultant filter, the convolution process is arranged (e.g.,roller spacing and compression levels) to achieve a preferred height ineach mirror image fiber filter sheet that ranges from 1.5 to 4.0 inchesand more preferably 1.75 to 3.0 inches (which range generally holds trueas well for the resultant filter as any post processing of the filtersheet preferably involves no additional extensive compression) and morepreferable about 2 inches. Once the fiber batt has sufficiently “set”for convolution in the convoluter and there a considered a minimal(e.g., non-significant and/or non-noticeable) loss in height due toconvoluter compression between original fiber batt and resultant mirrorimage fiber filter sheets for preferred embodiments of the invention.

As having too low a basis weight for a given thickness at the higher endof the above thicknesses could degrade the filtering effect in someinstances, it is desirable for some applications to use the lower endbasis weight values in conjunction with lower end thickness ranges whilethe higher end basis weight are generally not subject to the sameconcerns. Accordingly, a basis weight of 600 g/m² with a pre-convolutionloft or thickness range of 40 mm to 65 mm, or 900 g/m² with apre-convolution loft or thickness range of 40 to 100 mm, or 1200 g/m²with a loft or thickness range of 50 mm to 140 mm, or 1500 g/m² with aloft or thickness range of 75 mm to 165 mm, or 1800 g/m² with a loft orthickness range of 90 mm to 190 mm represent preferred basisweight/thickness combinations under the present invention. Morepreferable combinations include, for example, a basis weight 900 g/m²(with a preferred thickness or loft range of 75 mm to 100 mm) to 1500g/m² (with a preferred thickness or loft range of 125 mm to 165 mm).Additional preferred combinations deemed well suited for many intendeduses of the present application include weight/thickness combinations of1800 g/m² (with a preferred thickness or loft range of 125 mm to 190 mm)to 2100 g/m² (with a preferred thickness or loft range of 175 mm to 225mm). The foregoing thickness ranges show preferred ranges relative tothe noted basis weights that are well suited for typical intended usagesof the present invention, but thickness levels above and below the notedranges are also possible relative to the noted basis weights and viceversa depending of the desired filter requirements and intended usage.

Thus, in accordance with the present invention a highloft density levelof 8 Kg/m³ to 24 Kg/m³ or, more preferably 7.5 Kg/m³ to 15 Kg/m³, (andeven more preferably, 9 Kg/m³ to 12 Kg/m³) is well suited for thefiltering purposes of the present invention. The above-noted high loftdensity valves are relative to a pre-convolution state of the fiber battor in other words the condition of the fiber layer before beingcompressed and cut during the convolution process (although as notedabove for preferred embodiments of the invention there is deemed anegligible difference between the two states upon rebound).

The preferred denier values of the fibers used in the nonwoven fiberblend of the present invention preferably are 15 denier or more, morepreferably 25 denier or more, with 25 to 100 being a preferred range.Also, a 30 to 50 denier value as in a 40 denier, is preferred as themajority percentage of blend. For example, in a preferred filter, amajority blend of 40 denier is considered most desirable although usinghigher deniers is included within the scope of the invention, butefficiencies will fall. Likewise using lower deniers is possible underthe present invention but will cause the filter to load prematurely formany intended uses. Blends of fibers using 15 denier through 100 denierare featured under the present invention. As an example, a blend of 15and 100 deniers can render similar results of an all 40 denier blend(e.g. an averaging providing about a 40 denier average). However, an allabout 40 denier blend is preferable to a mix and matching of manydifferent denier types to achieve the average (although the presentinvention subject matter is inclusive of such a mixing of differentdeniers in an effort to achieve a desired denier value average for amajority of the blend, for example). For example, from the standpoint ofease of blending and processing use of a mostly 40 denier blend is thepreferred technique. An additional example, includes a blend of fiberswith no 15 denier but only 40 denier or higher together with apercentage of binder fiber.

The non-mechanical high loft bonding (or means for bonding the fiberblend) utilized in the present invention is helpful in providing thedesired filtering characteristics, which facilitates the achieving ofthe high efficiency filter product described above and below. Whilethermal and/or spray resin bonding represent the preferred bindingtechnique or binding means utilized in the present invention (e.g., suchtechniques help in maintaining the desired highloft attributes),combinations or sub-combinations or individual binding techniques suchas mechanical, thermal and/or chemical bonding techniques may be reliedupon as the means for binding the fibers to provide the fiber batt. Asan additional example of a combination of techniques which retains thedesired highloft attributes, mechanical bonding equipment may be used inconjunction with other non-mechanical bonding techniques to providevarious finished batts. For example, one side (e.g., top or bottom) ofthe material can be made of higher density using mechanical techniqueswhile the other side remains lofty. This creates various airflowproperties. However, having a constant density throughout the fiber battis preferred. The loft values provided herein can thus be considered torepresent the value of the non-mechanically bonded portion or area ofthe highloft material when other than a consistent density fiber battfilter is to be produced.

If mechanical bonding is used in conjunction with one or more of theabove noted non-mechanical bonding techniques, it is preferably usedonly in a minor context such as only affecting a small percentage of theoverall portion (volume or area) of the filter (e.g. less than 10%).Also, if mechanical bonding techniques are employed over a larger areaof the material, a minor degree of bonding by mechanical means ispreferred to essentially preserve initial loft and density values (e.g.,a resultant loft or thickness value that is within 20% of one that isentirely free of the finished goods mechanical bonding supplementation).As an example, mechanical bonding can be provided at the edging of thefilter sheet to facilitate resultant filter attachment to a peripherybased support structure.

In chemical bonding, a resin or adhesive, typically in latex form, issprayed on the carded web and then dried and/or cured to bind the fiberstogether in their current orientation. The substance sprayed acts as a“glue” holding the fibers together and producing bond points at theintersection or the point where two or more fibers are in contact.Saturation bonding is similar except the web is immersed into a bath ofresin instead of the spray application of the resin. While the sprayapplication and saturation through immersion are possible techniquesunder the present invention, they are less preferable than the belowdescribed thermal bonding means such as a thermal bonding with the useof binder fibers. The chemical binder method involving a sprayapplication has environmental issues that also contribute to thesaturation method not being the preferred method of binding for manyapplications and also issues of reaching the interior with bindingchemical. For example, the thickness of the preferably sized non-wovenbatts do not lend themselves well for chemical bonding spray orimmersion. Spray bonding batts of these thicknesses can result in heavyapplications of resin on the surface and virtually none in the center.Also, the softer center may not convolute well. Saturate bonding canalso affect the final loft of the non-woven batt before convoluting andthus is less preferable due to such compression issues. As noted,however, the present invention also includes, within its scope, thesetechniques as well as hybrid combinations of, for example, thermal andchemical bonding in alternate, less preferred, embodiments.

Thermal bonding utilizes binder fiber that upon heating provides thebinding means amongst the fibers in the fiber recipe utilized. This caninclude binder fibers binding together as well as non-binding fibersbeing bound together directly or indirectly by way of a binder fiber inthe recipe. A recipe have binder fiber (e.g., from 15 to 50% of theoverall weight of fibers utilized in a recipe is preferred) representsthe preferred binding means under the present invention. Binder fiber istypically composed of polymer(s) that have a lower melting point thanthe “fill” fibers (if utilized) or other fibers in the blend (ifutilized—as an all binder fiber embodiment is featured as an alternateembodiment under the present invention). The binder fiber then melts inthe presence of heat in a subsequent processing step. The binder, inmolten form in the presence of heat, flows to the intersection of fibersand upon cooling re-hardens and forms a bond. These bonds allow thefibers to remain in their current orientation. Binder fiber can be asolid, single polymer fiber with a significant lower melting point thanthe fill fibers in the blend. The binder can also be a sheath/core fiberwhereas the sheath component is a polymer of low melting point with thecore being a polymer of a relatively higher melting point. A core binderfiber as the binding fiber is preferred under the present invention.

These thermal/adhesive bonding techniques produce finished materialswith significantly higher loft or thicknesses for the same basis weightthan mechanical bonding means. The thickness and loft of the product isbeneficial in the preferred usage of the present invention. In apreferred embodiment invention the fiber bonding means is provided by abinder fiber with the binder fiber preferably being 15% more of theoverall fiber blend weight with 25% to 50% binder fiber percentage beingpreferred and with 25 to 35% being a more preferred range for manyapplications. Binder fiber (e.g., commercial sheath/core variety) denierrange includes, for example, 2 denier to 15 denier with the preferredrange being from 4 to 15 denier.

The high loft non-woven barrier material of the present invention can bemanufactured in a variety of ways some of which are described in the“Non-Woven Textile Fabrics” section in the Kirk-Othmer “Encyclopedia ofChemical Technology” 3^(rd) Ed. Vol. 16 pgs 72-124, which section isincorporated herein by reference. A preferred manufacturing process forforming the barrier of the present involves passing supplied fiber massfrom a compressed bale by way of a feed device, such as a feed conveyoror rolls, to an opener designed to break apart the fiber mass, thusinitiating fiber opening and separation, passing opened fiber mass to aweigh device, continuous or batch, designed to weigh the opened fibermass, blending weighed amounts of the desired amount of opened fibermass in a blender to achieve a homogeneous blend of the desired amountsof the opened fiber material. The manufacturing process further includespassing the opened, weighed and blended fiber mass to a non-wovenforming device such as a carding device to form a web of non-wovenmaterial. Preferably the process involves cross lapping or layering websin a cross lapping device of the like until the desired thickness ofpredetermined basis weight non-woven highloft material is obtained.

Preferably each of the above relied upon stages is controlled andcoordinated through use of a central processor in communication with thevarious pieces of “equipment in the overall system.” This allows, forexample, an operator to input a desired blend recipe having the abovenoted desired percentage by weight amounts of the desired categories ofmaterial to be used and to control the basis weight of the blended fiberand thickness (e.g., amount of cross-lapping webs) of the desired layerof non-woven highloft material. The opening and blending of theaforementioned fibers is preferably carried out with high quality fiberopeners and blenders that are designed for accurately producing ahomogeneous blend of the above described fibers. Suitable opening andblending equipment includes a bale opener and fine opener manufacturedby “Fiber Controls” of Gastonia, N.C. and a blended fiber reserve feedchute manufactured by “Dilo Group” of Bremen, Germany. Opening ispreferably carried out through the use of various stages of openingwherein each successive stage represents finer opening and more fiberseparation to help in achieving a more homogeneous and accurateresultant blend. Following the various opening stages, all opened fibercomponents for use in the desired resultant blend are preferably weighedbefore blending to ensure accurate percentage of blend. This blendingstep can be achieved without weighing but poor blending can potentiallynegatively affect the performance of the filter of the present inventionby allowing relative low concentrations of key components in an area ofthe material or too high “blocking” concentrations in other areas.

Blending involves, for example, mixing the weighed fibers throughlayering of the weighed components and feeding through a blending rollbeater (which can be configured using pins or saw tooth wire) turning ata high rate of speed relative to the speed of the weighed components andtransported into a chute feed or reserve feed hopper, such as the“Direct Feed” brand hopper sold by Dilo Group of Bremen, Germany.Further blending can be accomplished by processing the pre-blendedcomponents through a reserve blending mixing chamber such as the Type 99Reserve Chamber sold by Fiber Controls, Inc. of Gastonia, N.C.

The opened and blended fibers are then preferably processed through ahigh quality non-woven carding device (e.g., a Type 1866 HighloftNon-woven Carding device sold by Dilo Group of Bremen, Germany) and theresulting web is crosslapped or layered (e.g., by way of a CL-4000series crosslapper sold by Autefa, Germany) to form a highloft web. In atypical carding process there is utilized a series of wire wound rollsturning at various speeds (depending on the application and product tobe carded) which can be controlled by the control processor. Mostcarding devices are comprised of a breaker section with a large mainroller with smaller diameter rolls positioned around the arc of the mainroller. A second, larger main roller is configured with a doffer rollbetween the breaker main and itself. A series of smaller rollers areconfigured around the second main roller. Two doffer rollers positionedover top one another in a vertical arrangement remove the carded webfrom the carding device. Various configurations of carding devices areavailable. Speeds of the rolls in a given carding devices are usuallyadjustable to allow for processing a wide range of fibers and deniers.In the carding device, the fiber is carded or combed by the action ofthe moving saw-tooth wire against the fiber mat being fed through themachine. This same process is accomplished through garneting and othervarious web forming machinery such as airlay webs. The web exiting thecarding devices or web former can be used directly or can becrosslapped, vertically or horizontally, to build product loft orthickness and weight. Crosslapping layers or stacks of the continuouscard web allows for the formation of non-woven material to variousdesired thicknesses and weights. The web, in one embodiment of theinvention, incorporating binding fiber, is carried through a forced air,gas-fired continuous oven with temperatures up to 500° F. so thatbonding of the web takes place. Bonding temperatures are dependent onthe binder components in the blends. The material is then subjected tofinal processing such as having the material rolled on rolls and slit towidth per application to provide a fiber batt to be received by theconvolutor or alternate contoured three-dimensional surface formingmeans. The material can also be cut into panel size pieces depending onspecific applications. For example, the output material, if not alreadyin the desired shape and size, can be cut or otherwise altered to makeit suitable for feeding into a convoluter, for convoluting fiber filtersheets in accordance with a preferred three dimensional surface formingmeans under the present invention.

The above described preferred “equipment assemblage” is capable ofproducing highloft nonwoven fiber blends with weights of 40 g/m² (with,for example, thickness range of 5 mm to 10 mm) through 1800 g/m² andhigher (with, for example, a thickness or loft range of 150 mm to 250 mmand higher.)

Convolution/Surface Pattern

With reference to FIGS. 2 and 3, there is illustrated an example of asuitable convolution assembly 52 suited for convoluting fiber batt 55 toachieve a pair of the fiber sheets 55A and 55B from which the fiberfilter of the present invention is produced. In the present applicationthe following terminology is utilized to facilitate reference todifferent states of the filter material involved; with “fiber batt”preferably being the material produced by the high loft non-woven fiberlayer formation equipment or means (e.g., cross lapping or layering websin a cross lapping device or the like until the desired thickness ofpredetermined basis weight non-woven highloft described above). Thus,the fiber batt is the material to be fed to roller set 53 and subjectedto the compressive tool die sets 54A and 54B provided on the respectiverollers 53A and 53B. The individual projection members 54A and 54B ofthe respective tool die sets are preferably arranged to providesufficient compression projections and reception cavities as to pushportions of the fiber batt lying above the blade 57 plane below theblade plane and portions of the fiber batt lying below the blade planeabove the blade plane as to generate a preferred peak and valleyarrangement as in the peak and valley mirror image arrangementrepresented by fiber filter sheets 55A and 55B. As shown in FIG. 2,blade 57 is supported by a wedge shaped blade holder 59 with bladeposition adjustment means for movement of the blade forward or backalong the plane (shown horizontal for this embodiment) occupied by thetip of blade 57.

Depending on the thickness of fiber batt 55, this can include a spacingbetween the rollers 53A and 53B leading to the tool projections (54A and54B) being in an intermeshing arrangement where the tool projection ofone roller extends into a cavity C formed between an adjacent pair oftool projections on the opposite roller. FIG. 3 further illustratesroller adjustment system 65 shown with a hydraulic member 67 used foradjusting the relative spacing between the opposite roller's outercircumference. With the above-described preferred thickness range (e.g.,1.0 to 9.0 inches) in the fiber batt being fed to the convoluting rollerset, the minimum preferred spacing between the outermost circumferencerepresented by the outer end of the tool projections for each rollranges from plus 0.375 inches to plus 0.125 inches with “plus” beingindicative of a spacing between respective circumferences represented bythe tips of respective projections in the tool set on the rollers asopposed to a minus having intermeshing tool sets which is a suitable setup for some embodiments but not preferred.

The term “fiber filter sheets” is thus representative of the output ofthe convolution equipment which is preferably in the form of a mirrorimage pair. The term “filter” by itself is used below in reference tothe resultant filter(s) derived from the fiber filter sheets, whichfilters are in a ready for use state (e.g., cut up squares of a fiberfilter sheet or the end use filter can be one in the same as the fiberfilter sheet structure when the filter framework structure is suited forsupporting such a fiber filter sheet without further modification in thesheet and/or the convoluter output provides ready for immediate filteruse fiber filter sheets).

The present invention preferably features convolution equipment thatprovides the capability of high throughput in the manufacture of fibersheets as in sheets being generated at a rate of 150 ft./min. line feetin the longitudinal feed direction, and with a fiber filter sheet width(transverse to feed direction) of about 36 to 80 inches beingillustrative and with the feed length being preferably sheets of 100inches or a feed provided from an even greater length roll as in, forexample, up to a 50 foot roll. The width is preferably generally equalto the infeed of the fiber batt although subsequent width processing isalso featured under the present invention. The filters can also be sizedfor insertion within a support frame such as that utilized in the spraybooth illustrated in FIG. 1 of the present application.

After the fiber batt is convoluted to generate opposing fiber filtersheets, the fiber filter sheets are separated and then, if applicable tothe desired embodiment, subjected to a filter formation process (e.g., acutting operation for the desized end use size) or, depending on the endusage envisioned, a complete fiber filter sheet can be relied upon.

As also seen from FIG. 3 the projection peaks P1, P2 . . . etc., in onefiber filter sheet correspond with the valleys V1, V2 . . . etc., in theopposite layer, although upon separation and proper orientation twoessentially mirror image fiber sheets are provided.

While the illustrated convoluter assembly of FIG. 3 illustrates apreferred convoluting assembly, other three dimensional surface formingmeans are featured under the present invention including alternateconvolution means such as conveyor belts functioning as rollers (aroller/conveyor belt combination of opposite positioned conveyors) aswell as a sliding plate arrangement (a pair of sliding and/or onestationary plates) or a sliding or stationary plate used in conjunctionwith a conveyer belt or individual roller, or the like or alternatecontoured surface forming means as in grinding or cutting (mechanical asin a fixed blade with moving substrate or non-mechanical application asin a laser) and the like. Also, as will become more apparent below, therecipe of the fiber batt under the present invention is also suited foruse in other three dimensional contoured surface forming means as in amolding or calendar process, but one of the benefits of the presentinvention is to have a fiber batt that is well suited for use with aconvolution means for efficiency, easy operation, etc.

With reference to FIGS. 4 and 5, there is seen a representative filtersheet 55A shown with a preferred filter sheet pattern of the presentinvention comprising a zig-zag or sinusoidal ridge, peak and valleycombination across the exposed surface of the filter sheet. The FIG. 4representation is intended to show a generic presentation of thepreferred general sheet pattern with the disclosure below providing somepreferred spacing and height arrangements (preferably the surfacepattern for the fiber filter sheet carries directly over to the filtersheet itself). Also, while a continuous pattern is shown across theillustrated exposed surface of the fiber filter sheet, as an example ofa preferred embodiment; with variations in the convoluter tooling it ispossible to have different zones along the length (common with feeddirection of sheet) or along the width (transverse to feed direction) orboth. This would provide for different flow patterns in one commonfilter or the ability to provide a variety of filter types from onefilter sheet. Also, there can be provided non-convoluted peripheraledging areas if, for example, a peripheral edge capture supportstructure is utilized. Again, however, from the standpoint of ease inmanufacture as well as maintaining the preferred overall density andsurface area presentation over the entire, exposed filter surface, acommon pattern over the entire area subject to flow exposure ispreferred and preferably over the entire flow contour side of thefilter.

There is further designated in FIGS. 4 and 6 the following referencenumbers and/or letters having the characteristics described below inTable I (which values are provided as representations of preferredembodiments and are not intended to be limiting relative to the generalsubject matter of the present invention).

TABLE I Illustrative Range (all values in Table I in Most inches unlessPreferred otherwise Preferred Range (or Sample Ref. Descriptionindicated) Range value) 4 TH Total fiber 0.75-6.0  1.0-4.0 2.0 ± .50 2.0filter sheet thickness BH Base height 0.375-3.0  0.5-2.0 1.0 ± .25 1.0of fiber filter sheet PH Peak height .375-3.0   .5-2.0 1.0 ± .25 1.0 offbase also (preferably equal to valley height) PPW Peak-to-peak 4.0 ± 1.54.0 ± 1.0 4.0 ± .50 4.0 distance along sheet length for illustratedzig-zag pattern PPL Peak-to-peak 2.0 ± .75 2.0 ± .50 2.0 ± .25 2.0distance between ridgers across sheet width PAN Slope angle  40-65° 45-60° 52.5° ± 2.5°  52.5° [in degrees] for peak CV Peak 0.4-0.6.45-.55 .50 .50 curvature (valley preferably same as peak) valuedetermined by measurement of Autocad drawing L1 Length of  5-80 10-40 20 ± 2.5 20 resultant filter produced W1 Width of  5-80 10-40  20 ± 2.520 resultant filter produced

In the discussion above the reference to width “W” is made relative tothe distance between the side edges extending in common with thedirection of sheet travel through the convoluter while length “L” isused relative to the distance between the upstream and downstream endsof the filter sheet passing through the convoluter (or the furtherprocessed cut ends of the filter sheet is reduced in length for filtersizing). Also, the “in-use” filter orientation is preferably with theridges running vertically and the frame support vertically extendingalthough alternate arrangements and combinations are possible

Thus, as seen from FIGS. 4 and 6 the fiber filter sheet 122 comprises anon-woven fiber material preferably being a high loft fiber filtermaterial having a composition such as that described above and havingbeen subjected to a convolution process like that described above forFIGS. 2 and 3. Fiber sheet 122 features opposing side walls 123 and 124between which are positioned a plurality of projections “PA” (PA1, PA2 .. . etc.). As noted above, side walls 123 and 124 preferably representthe side edges extending in the same direction as the feed into rollerset direction whereas side walls 125 and 127 represent the upstream anddownstream end walls of the resultant filter. Projections are preferablyin the form of continuous ridges R that are serially spaced across thewidth “W” while running along the length L of the fiber sheet. As shown,a preferred embodiment features ridges that extend continuously (e.g.,80 inches or more of length non-interrupted) between end walls 125 and127.

While FIG. 4 shows a top planar view of filter sheet 122, as noted aboveit also illustrates a preferred vertical orientation of the filter sheetupon the filter sheet being placed in a ready-to-use state on a filtersupport framework such as that shown in FIG. 1B. The end walls (125,127) are preferably the walls that are cut to provide the desired lengthof fiber sheet if not already of the desired size upon convoluter orsurface forming means output. Also, while side walls 123 and 127 aregenerally aligned with the end walls of the rollers duringconvolution—it being noted, however, that with proper toolingalterations the length (“L”) and width (“W”) references for the sheetorientation of FIG. 4 can be reversed in a convolution feed though,although the preferred “in use” arrangement is as described above.Alternatively, multiple rows of commonly configured filter sheets can beoutput, as well as other variations. For example, while the illustratedembodiments shows a convoluter roller generally having an axial lengthabout equal to the desired resultant filter width “W” with cutting tolength required at the ends only (as for a roll feed), alternatearrangements are featured under the present invention as in the rollerlength being greater as in about two (or more) times the final filterwidth for increasing production output with a added longitudinal lengthcutter. Sheet 120 is shown as having length L1 and width W1 withillustrative values for the same provided in Table I above.

As seen from FIGS. 4 to 6A the convolution process imparts athree-dimensional upper surface 130 in the filter sheet, whichpreferably represents the initial or upstream contact surface of thefilter when in use. The three dimensional convolute surface 130, asdescribed above, comprises a projection ridge/recess pattern extendingcontinuously along the longitudinal direction L. Further, the individualprojections and recesses are shown as preferably repeating in equalspacing fashion from side wall 123 to side wall 124 in the transversedirection W. Further, the individual projection recess combinations arepreferably arranged in a peak/valley combination with a preferredembodiment having the peaks in valleys in a zig-zag (or sinusoidal)pattern (e.g., each peak ridge having equal peak ridge slope extensionsextending to opposite sides of a longitudinally bi-sect line passingthrough that peak ridge).

The inventors have discovered that attention to the surface patternhelps improve the performance filter characteristics as in particulateremoval efficiency, holding capacity and pressure drop. For example, ithas been determined that the zig-zag pattern improves on holdingcapacity relative to other surface patterns as in a convoluted“egg-crate” surface pattern found on many foam convoluted products(although for some uses, and with preferred recipe mix advantages, anegg-crate design or alternate designs represent subject matter of thepresent invention). Further, as explained in greater detail below, evendeviations in the relative characteristics between one zig-zag shapedpeak/valley surface pattern to another can enhance the filtercharacteristics as in paint removal efficiency. This includes forexample the relative valley depth, peak height, peak configuration(e.g., the slope of attack) in the flow direction through the filter aswell as the peak/valley arrangement across the width W and along thelength L as in the peak amplitude along a common row and spacingdimension from row to row is a series of rows.

To illustrate the advantageous embodiments of the present invention, adiscussion below is provided as to preferred fiber batt characteristicswell suited for convolution in a convoluter to provide a filter sheetfor filter formation. Further provided is a discussion of a preferredsurface pattern of the filter fiber sheet which, particularly incombination with the described fiber batt characteristics, provides ahighly efficient and highly operational filter.

Preferred recipe blends for use in formation of a fiber batt inaccordance with the subject matter of the present invention as well assome comparison samples are set out in the following table(s).

TABLE II Most Preferred Range of % Preferred Fiber Types Preferred as inBatt Preferred Range or Reference Fiber Blend in This Denier Blend orRange % as Value as in Letter Description Category Range Recipe in BlendBlend A First base fiber Polyester or 15 denier to 15% to 50% 20% to 50%10% to 25% comprised of one Other Man 40 denier or more of the MadeFibers following fiber types B Second base fiber Polyester or 40 denierto 15% to 85% 30% to 75% 40% to 60% comprised of one Other Man 100denier or more of the Made Fibers following types C Binder Fiber BinderFiber - 4 denier to 15 15% to 50% 20% to 40% 25% to 35% comprised of one50%/50% denier or more of the Sheath/Core following types Or 100% lowermelt component BW Basis Weight of Post n/a 600 g/sqm to 1000 g/sqm to1200 g/sqm to Fiber Batt convolute 2100 g/sqm 2000 g/sqm 1800 g/sqmshould be evenly distributed. DE Density of Fiber n/a n/a 8.0 to 24.0Kg/ 9.0 to 12.0 Kg/ 7.5 to 15.0 Kg/ Batt sqm sqm sqm BT Batt thickness(pre n/a n/a 3 to 8 inches 3.5 to 5.5 4 inches convolution) inches

The above ranges values represent some of the preferred range values orvalues for preferred embodiments. However, as described above a varietyof blend combinations are featured under the present invention. Thus, inalternate embodiments, the above referenced categories A and/or B (seeleft column can be dropped down in value or dropped out (0%) as inreliance on 100% binder material (category C) and/or the inclusion ofone or any subcombination of A, B and C as, for example, using a sprayfor binder purposes in place or in addition to the thermal bindermaterial in category C. However, the use of all three of categories A, Band C represents a preferred embodiment of the present invention.

Provided below are some sample description for filters for which theirperformance was tested.

Sample 1 1.5 oz Thermal Paint Arrestor Recipe Blend Percentage of FiberRelative to Overall Weight of all Product Description Fiber DescriptionFibers in Recipe First Base Fiber A Stein 40 denier¹ 55% Second BaseFiber B “Invista” 15 denier² 20% Binder Fiber C “Fibertex” 4 denierbinder³ 25% Surface characteristic Planar upstream surface -(non-convoluted and non-three dimensional) BT Overall Filter Thickness1.5 (inches) BW Basis Weight of Fiber Batt 450 g/sqm ¹Stein 40 denierfiber is available from Stein Fibers LTD of Albany, NY, USA and has thefollowing qualities. 40 denier, 2″ to 3″ staple length preferred, 6 cpi(crimps per inch) to 10 cpi preferred, non-siliconized finish. ²InvistaT295 15 denier fiber is available from Invista located in Wichita, KS,USA and has the following qualities. 15 denier, 2″ to 3″ staple lengthpreferred, 6 cpi to 10 cpi preferred, non siliconized finish preferred.³Fibertex 4 denier binder fiber is available from Fibertex A/S ofAalborg, Denmark; 4 denier, 50% sheath - 50% core preferred, 2″ staplepreferred.

Sample 2 3.25 oz/ft² Pre-convoluted Recipe Blend Percentage of FiberRelative to Overall Weight of all Product Description Fiber DescriptionFibers in Recipe A Stein 40 denier 55% B “Invista” T295 15 denier² 20% C“Fibertex” 4d denier binder³ 25% BT1 Pre-convolution Thickness 3.25″(inches) of Fiber Batt BW Basis Weight of Fiber Batt 975 g/sqm (for postconvolution each piece is approximately half that value afterconvoluting)

Comparison Sample 3 Product Description “Paint Pocket” Material Utilized“Paint Pocket Product” Waffle or slit and stretch ¾ inch non-wovenpolyester with waffle layer pattern Backing layer ¼ inch non-wovenpolyester pad adhered to waffle layer

Sample 4 Carpenter “TOP” Recipe Blend Percentage of Fiber Relative toOverall Weight of all Product Description Fiber Description Fibers inRecipe A Stein 40 denier 55% B Invista T295 15 denier 20% C Fibertex 4dbinder 25% BT Pre-convolution Thickness 4.25″ (inches) BW Basis Weightof Fiber Batt 1500 g/sqm (the post convolution valve is approximatelyhalf)

The testing performed is set forth in the description in conjunctionwith the noted corresponding figures.

Test 1

A test was carried out on a filter having the characteristics of Sample1 with the filter being a flat surface (both upstream and downstreamsurfaces).

Table III below sets forth the test information for the filter of Sample1 in use in a paint spray booth environment.

TABLE III Test Information (Sample 1) Filter Description Sample 1Material (20″ × 20″ pad) Paint Description High Solids Banking Enamel(Sherwin Williams) Paint Spray Method Conventional Air gun at 40 psiSpray Feed Rate 138 gr/min/130 cc/min Air Velocity 150 fpm

TABLE IV Test Results (Sample 1) Initial pressure drop of clean test0.05 in. water filter Final pressure drop of loaded test 0.53 in waterfilter Paint holding capacity of test filter 1663 grams (3.7 lbs) Paintrun off 89 g Weight gain - final filter (second 6.7 g = penetration inline - downstream) Average removal efficiency of 99.62% test filterThese test results are also shown in FIGS. 1C to 1F.

The tests conducted were based on ASHRAE 52.1 which is test standardincorporated herein by reference but modified to approximate the paintenvironment. This arrangement is considered the standard of the industryfor this type of application.

FIG. 1C shows the pressure drop of the filter of Sample 1 in a cleanstate with a flow through air velocity range of 0 to 250 feet-per-minuteor fpm. FIG. 1C shows an initial pressure drop of 0.05 in water at anflow through air velocity of 150 feet per minute or “fpm”.

FIG. 1D shows the pressure drop for the filter in Sample 1 versus theweight of paint fed through, starting at the above-noted 0.05 in H₂O fora clean filter and rising sharply to a loaded test filter final pressuredrop of 0.53 in water. It is noted that maximum capacity is achieved byrunning the test until the pressure drop reaches 0.50 in water, or 32minutes of spraying. Based on the above-described test results and FIG.1D the maximum load state exists with the filter having shown a paintholding capacity of 1663 g. It is noted that 1663 g is the final weighton the filter, while the FIG. 1D has a chart with an x-axis denotingtotal weight of paint fed. The valve value of 1662 g is based on thefact that not all paint fed ends up on filter or in the run-off trough.

In this test there was also experienced a 89 g paint run off which is ameasured amount based on the paint that runs off the filter into atrough.

There is further shown in FIG. 1E the amount of paint not blocked byfilter and which reach or “penetrates” the second or downstream filter.For Example 1 the amount of penetration is 6.7 grams of paint which,like the holding capacity calculation for the first filter is carriedout by way of a before and after precision weighing of the filterinvolved. In the testing, the final filter in the test is not the sameas the first, but instead is a conventional filter designed for highefficiency to capture as much paint as possible to give an accurateassessment of the paint traveling through the test filter.

FIG. 1F shows a graph for the removal efficiency for various data pointswhich correspond to specific times during the test. The first threepoints are taken every 2 minutes. The 4^(th) point is taken at 10minutes, the fifth point at 16 minutes, and the final point 10 minuteslater.

Test 2

A test was carried out on a filter having the characteristics of Sample2 with the filter being a convoluted surface having the generalconvolution pattern represented by FIG. 4 but having “smaller”characteristics as compared to the above and below described Sample 4characteristics relative to, for example, peak height and spacing asdescribed above.

Thus, with reference to the schematic depictions in FIGS. 4 and 5 therecan be seen a zig-zag convolution pattern formed in a filter fiber sheetto produce the filter having the “smaller” characteristics as comparedto the more preferred Sample 4 embodiment described below. Table V belowsets forth the test information for the filter Sample 2 in use in apaint spray booth environment while Table V1 provides the test resultsfor Sample 2.

TABLE V Test Information (Sample 2) Filter Description Sample 1 Material(20″ × 20″ pad) Paint Description High Solids Banking Enamel (SherwinWilliams) Paint Spray Method Conventional Air gun at 40 psi Spray FeedRate 138 gr/min/130 cc/min Air Velocity 150 fpm

TABLE VI Test Results (Sample 2) Initial pressure drop of clean test0.11 in. water filter Final pressure drop of loaded test 0.52 in waterfilter Paint holding capacity of test filter 2207 grams (4.9 lb.) Paintrun off 97 g Weight gain - final filter (second 5.4 g = penetration inline - downstream) Average removal efficiency of 99.77% test filterDescription of Sample 2 Test and Results

FIG. 7A shows the pressure drop of a clean “Sample 2” filter (i.e., theconvoluted filter with the convolution surface on the upstream siderelative to air flow and the non-convoluted surface on the downstreamside—a preferred arrangement for the filter although oppositemulti-sided convoluted surface filter embodiments are also contemplatedin the event of, for example, a reversible flow filtering system). Asseen from FIG. 7A, for an air flow of 150 FPM there was an initialpressure drop of 0.11 in water for the clean filter.

FIG. 7B shows the pressure drop for the filter in Sample 2 versus theweight of paint fed through starting at the above-noted clean filterpressure drop of 0.11 in water and showing a loaded filter, finalpressure drop of 0.52 in water.

Paint holding capacity of 2207 g was also in conjunction with a 97 gpaint run-off.

FIG. 7C shows a penetration value or the amount of weight gain in thefinal filter of 5.4 g.

FIG. 7D shows the average removal efficiency of the test filterrepresented by Sample 2 of 99.77% determined by (2207/(2207+97+5.4)).When the pressure drop of the loaded filter exceeds 0.50 in water, thefilter can become too restrictive to maintain a desired airflow in thebooth and thus a filter change is deemed required as excessive run-offmeans more cleaning issues in the booth. Factors such as time to load upand how much run-off are some of the potential factors considered whendetermining whether a product is commercially acceptable or not.

As can be seen by a comparison of the non-convoluted Sample 1 filter andthe convoluted Sample 2 filter, although at the same general weightrange specification, the Sample 2 realized an increase of paint holdingcapacity of 1.2 lbs. to 4.9 lbs. relative to Sample 1. This is anincrease of 32% over the non-convoluted pad. Further testing hasrevealed that by increasing the weight to a pad weight of 2.0 oz/sqftafter convoluting, paint-holding capacity can be increased to 5.7 lbs.This is accomplished without lamination or varying the fiber blend anddensity within the matrix of the fiber. Thus, convoluting the surface ofthe fiber results in appreciable increases in paint holding capacitywithout having to vary blends, add additional webs, or vary the densitywithin the fiber bat.

As described in the background portion of the present application, whileSample 2 shows significant improvement over conventional filters,further improvements resulted in even better performance and quality andconsistency in the resultant end product filter produced under thepresent invention with an embodiment represented by Sample 4.

Test 3

To illustrate the improvements made over Sample 2, Test 3 was runwherein Sample 4 was produced and tests carried out. The characteristicsof the filter produced is described in Table VII below.

TABLE VII Ref. Description Sample 4 Values TH Filter sheet thickness2.0″ BH Base height of filter sheet 1.0″ PH Peak height off base also(preferably equal 1.0″ to valley height) PPW Peak-to-peak distanceacross sheet width 2.0″ PPL Peak-to-peak distance along length for 4.0″illustrated zig-zag pattern PAN Slope angle for peak 52.5° CV Peakcurvature (valley preferably same) .50 BTP POST-convolution Thickness(inches) 2.0″

The test carried out on Sample 4 is presented below

TABLE VIII Test information Sample 4 Filter Description ¾″ poly. wavesfront on 1 ¼″ backing white (this filter is formed as a monolithic fiberbody with a generally constant density and fiber make up both in overalldepth and across the width and length of the filter 20″ × 20″) PaintDescription High Solids Permaclad (Sherwin Williams Permaclad 2400)(same as Test 1) Paint Spray Method Conventional Air gun at 40 psi SprayFeed Rate 134 gr/min Air Velocity 150 FPM

TABLE IX Test Results (Sample 4) Initial pressure drop of clean test0.08 in. water filter Final pressure drop of loaded test 0.50 in waterfilter Weight gain on test filter and test 4160 g frame Paint holdingcapacity of test filter 3714 grams (8.2 lbs) Paint run off 446 g Weightgain - final filter (second 17.7 g = penetration in line - downstream)Average removal efficiency of 99.58% test filter

As seen from the above Test Result Table VIII and FIGS. 9A to 9D, Sample4 provided a filter having a paint holding capacity of 3714 g with aremoval efficiency of 99.58% which is workable in most systems. Thisholding capacity represents a distinct improvement when considering theease of manufacture and low expense associated with the production of afilter like in Sample 4. That is, the filter of Sample 4 represents ahigh performance filter that provides the operator with extended usageduration; thus reducing the amount of downtime an operator experiences.As also seen from the Sample 4 blend description above, the blend offiber deniers utilized in Sample 4 has a majority of fiber deniers inexcess of 15 denier with the preferred majority being 25 denier orhigher and more preferably a 40 denier fiber is utilized as the majoritypercentage of the blend. Suitable “base” fiber material is/arepreferably selected from one or any sub-combination of the followingfibers having chemical description such as polyester, and polypropyleneor the like. These types of fibers can be derived from a variety ofsources such as brand fibers of Wellman, DAK, Invista, Far EasternTextiles, Nanya. Also, deniers such as 40 to 100 denier are preferred.Also, the binder percentage is preferably 15% or higher and morepreferably 20 to 40% and more preferably from 25% to 30% with thepreferred binder being 50%/50% sheath core—polyester low meltsheath/polyester high melt sheath. Solid low melt polyester and/or solidpolypropylene binders or the like can be used as well. These types offibers can be obtained from a variety or sources with the followingbrand fibers representing some possible selections: Huvis, Sahan, Nanyabrand fibers.

Suitable “base A” fibers include one or any subcombinant of the abovematerials (noting that the “base” fiber material can constitute a singlefiber type or a fiber mix from the above-noted fiber group):

Suitable “base B” fibers include one or any sub-combination of the abovematerials (noting that the “base” fiber material can constitute a singlefiber type or a fiber mix from the above-noted fiber group):

Further the above blend discussion for Sample 4 represents a fiber battthat is well suited for crisp and high integrity convoluting. Theconvoluting process is preferably set up such that the rollers have acompression spacing and tooling as to generate three dimensional surfacepatterns having the characteristics described above.

Test 4

To help illustrate the advantages represented by the above-describedtest results for Sample 4 relative to paint arrester filters on themarket, Sample 3 was tested with Sample 3 representing a commercial“paint pocket” filter.

That is, a test was carried out on a filter having the characteristicsof a ¾ inch “waffle front” (believed to be a traditional slit andstretch formed diamond paint pocket forming arrangement) mounted on a ¼inch independent base pad of a common material. As seen from Table XIbelow, the paint description and paint spray method was the same as thatfor Test 3 (High-Solids Permaclad, Sherwin Williams Permaclad 2400) witha spray based on conventional air gun at 40 psi.

TABLE X Test Description (Sample 3) Filter Description Sample 3 ¾″polyester waffle front on 1 ¼″ polyester backing, white adhesivelaminate Paint Description High Solids Permaclad (Sherwin WilliamsPermaclad 2400) (same as Test 3) Paint Spray Method Conventional Air gunat 40 psi Spray Feed Rate 144 gr/min (it is noted that138 cc/min in test3 with same 130 cc/min round off for test 3 and 4 with the differencebeing considered within acceptable difference and thus not considered anappreciable added variable Air Velocity 150 FPM

TABLE XI Test Results (Sample 3) Initial pressure drop of clean test0.07 in. water filter Final pressure drop of loaded test 0.20 in waterfilter Weight gain on test filter and test 4073 g frame trough Paintholding capacity of test filter 3020 g (6.7 lbs) Paint run off 1053 gWeight gain - final filter (second 11.8 g = penetration in line -downstream) Average removal efficiency of 99.71% test filter

FIG. 8A shows the pressure drop of a clean Sample 3 filter (i.e., afilter having waffle like upstream surface with a solid backing layer).As seen from FIG. 8A for an air flow of 150 FPM there was an initialpressure drop of 0.07 for a clean test filter.

FIG. 8B shows the pressure drop for the filter 7 Sample 3 for a wetpaint feed through starting at the above-noted clean filter pressuredrop and showing a loaded filter final pressure drop of 0.20 in water.

A comparison of the test results for Sample 3 to comparison Sample 4shows an improved paint holding capacity relative to Sample 4 (3714 gfor Sample 4 and 3020 g for Sample 3). This being achieved with theadvantage of a highly efficient convolution surface formation techniqueas compared, for example, to a slit and stretch of an upper layerfollowed by adherence of that upper layer to a lower layer as isutilized in conventional filters to achieve a “waffle” surface contour.

Also, while a comparison of Sample 2 with the Sample 3 and 4 testsresults shows a lesser holding capacity in Sample 2, for someapplications the benefits of the rapid and greater efficiency in filterproduction method achievement with the above-described convolutionprocess (e.g., only a single process step consisting of a feed throughof a fiber batt through a pair of convoluters (typically a pair ofcompression rollers with circular die plates or cylinders as in aKirchoff AG convolutor roller set assembly, although other convolutionmeans are featured under the present invention including systems wherethe “rollers” are represented by conveyor belts or conveyerbelt/individual roller combinations, or tooling plates and conveyercombinations, as well as other convoluting equipment such as thatutilized in the convolution foam). That is, the formation of a finalfilter sheet having the final desired surface configuration comprises aone step feeding of the fiber batt through the convoluter wherein, notjust one, but two viable filter sheets are formed (showing a furtherefficiency in this form of convoluter based formation method). The endresult filter can then be simply formed under any conventional finalcutting operation if the filter sheet is not of the same configurationas the final filter characteristics (e.g., a filter sheet set versus afilter pad for insertion in a multi-operative frame wall supportstructure). In the former case the fiber batt has generally the sameperipheral configuration as the filter sheet and the filter sheet hasthe same general configuration as the end filter product such furthersecurement of layers and/or slitting and stretching of a layer is notrequired.

1. A filter, comprising: a fiber filter body comprising a base and aplurality of projections extending from said base, and wherein saidfiber filter body is a monolithic, non-woven fiber material body that iscomprised of a fiber blend having a convoluted surface with projectionsthat are in the form of zig-zag shaped rows which are separated byzig-zag shaped recesses, and wherein an interface region between eachprojection and supporting base is formed of a continuous blend of thefibers of said fiber blend, the improvement which comprises, said fiberfilter body has said projections extending for 50% or more of a totalthickness of said fiber filter body, and wherein said non-woven fiberfilter body has a basis weight of between 500 g/sqm to 1000 g/sqm with athickness of 1.5 inches to 3.0 inches.
 2. The filter of claim 1 whereinsaid non-woven fiber filter body has a basis weight of between 600 g/sqmto 900 g/sqm with a thickness of 1.75 to 2.5 inches.
 3. The filter ofclaim 1 wherein said projections represent about 60 to 85% of the heightof said fiber filter body.
 4. The filter of claim 3 wherein saidnon-woven fiber filter body has a basis weight of between 600 g/sqm to900 g/sqm with a thickness of 50 to 75 mm.
 5. The filter of claim 1wherein said projections are rounded peak rows with rows that are spacedapart by 2+/−0.75 inches.
 6. The filter of claim 1 wherein saidprojections have a side wall slope of 52.5°±2.5° on each side of theprojection as to provide, in cross-section, a rounded peak hill shape.7. The filter of claim 1 wherein said filter is a paint arrestor filterdesigned to provide a paint holding capacity of 6.8 pounds or more per20 inch by 20 inch area of said paint arrestor filter before reachingabout 0.50 pressure drop across said filter.
 8. A filter, comprising: afiber filter body comprising a base and a plurality of projectionsextending from said base, and wherein said fiber filter body is amonolithic, non-woven fiber material body that is comprised of a fiberblend having a convoluted surface with projections that are in the formof zig-zag shaped rows, the improvement which comprises, said fiberfilter body has a basis weight of between 500 g/sqm to 1000 g/sqm with athickness of 1.5 inches to 3.0 inches.
 9. The filter of claim 8 whereinsaid non-woven fiber filter body has a basis weight of between 600 g/sqmto 900 g/sqm with a thickness of 50 to 75 mm.
 10. The filter of claim 8wherein said projections represent about 60 to 85% of the height of saidfiber filter body.
 11. A method of using the filter of claim 1,comprising: providing the filter in a fluid flow path and removingmaterial in the fluid flow path with the filter.
 12. The method of claim11 wherein providing the filter includes providing the filter to asupport in a paint booth such that the filter functions as a paintarrestor.
 13. A filter, comprising: a fiber filter body comprising abase and a plurality of projections extending from said base, andwherein said fiber filter body is a monolithic, non-woven fiber materialbody that is comprised of a fiber blend having a convoluted surface withprojections that are in the form of zig-zag shaped rows, the improvementwhich comprises, said fiber filter body has said projections extendingfor 50% or more of a total thickness of said fiber filter body, andwherein the non-woven fiber filter body is comprised of a recipe offibers having a majority of the overall fibers of 40 denier to 100denier, and the fiber blend is essentially continuous in density from afirst fluid contact side to an opposite side of said filter relative tofluid flow through said filter, and wherein said non-woven fiber filterbody has a basis weight of between 500 g/sqm to 1050 g/sqm with athickness of 1.0 inches to 4.0 inches.
 14. The filter of claim 8 whereinthe non-woven fiber filter body is comprised of a recipe of fibers witha majority of the overall fibers being of 40 denier to 100 denier.
 15. Afilter, comprising: a fiber filter body comprising a base and aplurality of projections extending from said base, and wherein saidfiber filter body is a monolithic, non-woven fiber material body that iscomprised of a fiber blend having a convoluted surface with projectionsthat are in the form of rows with intermediate elongated recesses, theimprovement which comprises, said fiber filter body has said projectionsextending for 50% or more of a total thickness of said fiber filterbody, and wherein the non-woven fiber filter body is comprised of arecipe blend of polymer fibers of 10 to 50% by weight if fibers of 15denier to 40 denier; 15 to 85% by weight of fibers of 40 denier to 100denier and 15 to 50% by weight of binder fibers of 4 to 15 denier, andwherein said fiber filter body has a basis weight of between 500 g/sqmto 1050 g/sqm.
 16. The filter of claim 15 wherein the binder fiber is asheath-core binder fiber.
 17. The filter of claim 15 wherein the recipeincludes 20 to 50% polymer fibers of 15 denier to 40 denier; 30 to 75%of 40 denier to 100 denier and 20 to 40% of binder fiber of 4 to 15denier.
 18. The filter of claim 15 wherein the recipe includes 10 to 25%polymer fibers of 15 denier to 40 denier; 40 to 60% of 40 denier to 100denier and 25 to 35% of binder fiber of 4 to 15 denier.
 19. The filterof claim 1 wherein the zig-zag shaped row pattern provided on onesurface of the filter has about an equal base thickness to projectionheight ratio and wherein the rows and recesses between the rows arecontinuous with the rows having a 4.0 to +/−1.5 inch peak to peakdistance along a length distance which corresponds to a verticaldirection relative to the filter in use; a side to side row spacing of2.0+/−0.75 inches and wherein there is a slope angle of 40 to 65° inboth opposite side walls of each projection, which side walls each slopeoutward from a central region of the projection in going from a peak ofthe projection to the interface region of the projection with the base.20. The filter of claim 19 wherein the slope angle of each side wall is52.5+/−2.5°.
 21. A method of using the filter of claim 8, comprising:providing the filter in a fluid flow path and removing material in thefluid flow path with the filter.
 22. The method of claim 21 whereinproviding the filter includes providing the filter to a support in apaint booth such that the filter functions as a paint arrestor.
 23. Thefilter of claim 8 wherein the non-woven fiber filter body is comprisedof a common recipe blend of fibers having a majority of the overallfibers of 40 denier to 100 denier and with a binder fiber percentage inthe fiber recipe blend being 20 to 40% by weight at 4 to 15 denier. 24.The filter of claim 2 wherein the non-woven fiber filter body iscomprised of a recipe of fibers with a majority of the overall fibersbeing of 40 denier to 100 denier.
 25. The filter of claim 8 wherein thenon-woven fiber filter body is comprised of a recipe of polymer fibersof 10 to 50% by weight of fibers of 15 denier to 40 denier; 15 to 85% byweight of 40 denier to 100 denier and 15 to 50% by weight of binderfiber of 4 to 15 denier.
 26. The filter of claim 25 wherein the binderfiber is a sheath-core binder fiber.
 27. The filter of claim 25 whereinthe recipe includes 20 to 50% polymer fibers of 15 denier to 40 denier;30 to 75% of 40 denier to 100 denier and 20 to 40% of binder fiber of 4to 15 denier.
 28. The filter of claim 25 wherein the recipe includes 10to 25% polymer fibers of 15 denier to 40 denier; 40 to 60% of 40 denierto 100 denier and 25 to 35% of binder fiber of 4 to 15 denier.
 29. Thefilter of claim 8 wherein the zig-zag shaped row pattern provided on onesurface of the filter has about an equal base thickness to projectionheight ratio and wherein the rows are continuous with a 4.0 to +/−1.5inch peak to peak distance along a length distance which corresponds toa vertical direction relative to the filter in use; a side to side rowspacing of 2.0+/−0.75 inches and there is a slope angle of 40 to 65° inthe ridges.
 30. The filter of claim 29 wherein the slope is 52.5+/−2.5°.31. The filter of claim 1 wherein the monolithic, non-woven fibermaterial body is a non-laminated, single layer with an essentiallycontinuous density fiber blend from the convoluted surface to anopposite side of the single layer defining the base.
 32. The filter ofclaim 8 wherein the monolithic, non-woven fiber material body is anon-laminated, single layer with an essentially continuous density fiberblend from the convoluted surface to an opposite side of the singlelayer defining the base.
 33. The filter of claim 15 wherein the rows andrecesses are serpentine shaped.